You cannot determine the correct amount without knowing the specific transmission type. To find out:
1. Check your owner's manual: This is the best source of information. The manual will specify the transmission type and the correct fluid capacity.
2. Look at the transmission itself: The transmission usually has a tag or sticker with identification information, including the model number. You can then use this number to look up the capacity online (e.g., using a parts website or a Ford-specific forum).
3. Check the dipstick (if applicable): If the transmission has a dipstick, you can check the current level. However, this won't tell you the total capacity, only how much is currently in the transmission.
Without knowing the transmission type, any amount I give you would be a guess and could potentially damage your transmission. Find the transmission type first.